LT1-LT4 Modifications 1993-97 Gen II Small Block V8

LT1 fuel split

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Old 02-03-2013, 09:21 PM
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Often the splits narrow after getting the fuel trims closer. And, yes, those bogus ends will cause trims that far off if the tuner doesn't know what to do about it.
Old 02-04-2013, 02:42 PM
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I believe what he is asking is whether or not the Maf ends are causing the large split in fuel trims...which the answer is no. I do agree it makes it more difficult to setup the maf calibration but has nothing to with split fuel trims.
Old 02-04-2013, 04:20 PM
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Originally Posted by ws6_z28
I believe what he is asking is whether or not the Maf ends are causing the large split in fuel trims...which the answer is no. I do agree it makes it more difficult to setup the maf calibration but has nothing to with split fuel trims.
I think its time for a SIG update
Old 02-04-2013, 06:34 PM
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Originally Posted by ws6_z28
I believe what he is asking is whether or not the Maf ends are causing the large split in fuel trims...which the answer is no. I do agree it makes it more difficult to setup the maf calibration but has nothing to with split fuel trims.
As I thought I mentioned, when fuel trims are that far off, the splits often narrow when brought more in line. I have seen it many times over the years.
Old 02-04-2013, 07:12 PM
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Originally Posted by Green3spd
Also inspected that area. No luck.

Update:
I installed my facotory TB on it and the fuel split went from:
B1 +49.9(max on gauage)
B2 -17.x to -24.x

After stock TB:

B1 +49.9
B2 +32.x(cold) +5.x to +15.x(warm)

So I've still got a split, but it isn't a lean/rich split. Just Lean/not as lean lol
OK I don't argue that they can close slightly...but a differential this large isn't going to close within 5 or even ten. +49.9 is maxed and can be much higher. There's still another issue here.
Old 02-04-2013, 07:16 PM
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Originally Posted by ws6_z28
OK I don't argue that they can close slightly...but a differential this large isn't going to close within 5 or even ten. +49.9 is maxed and can be much higher. There's still another issue here.
I don't know how many years you have been tuning these full time, but I'm telling you I have seen them narrow dramatically, many times. That needs addressed before worrying about splits.
Old 02-04-2013, 07:34 PM
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I guess we'll just let time tell...but I don't see it closing up to within 10.
Old 02-04-2013, 07:59 PM
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Originally Posted by ws6_z28
I guess we'll just let time tell...but I don't see it closing up to within 10.
The time to address splits is after his tuner gets things closer. I have seen splits nearly that bad pretty much go away after getting it closer. Over rich doesn't usually widen fuel trim splits the way very lean does. He still needs to verify the mechanicals are correct. He could also have injector problems. I usually also swap the injectors side-to-side. Have found problems there too.
Old 02-10-2013, 11:36 PM
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Update:

Ohm'd all plug wires. Two had high resistance.
Replaced wires. ALONG with new plugs gapped to .35
Was told to inspect my MAF. It was a bit dirty, so I cleaned it. No change.
I took Ed's recommendation on using Factory metal MAF ends rather than my ported ends.
Installed them, NO change.

So complete run down-
FACTORY MAF
FACTORY THROTTLE BODY
NEW spark plugs gapped .35
NEW header gaskets
Checked for other exhaust leaks--NONE
SWAPPED injector sides
SWAPPED O2 sides
NEW O2's
Inspected O2 EXTENTIONS. LOOKED OK with no burns(will ohm wires if recommended)

Tuner & I played with tune this evening.
Added fuel several times(at one point up to 8% more) and it FIANALLY got B2 where it should be. But adding fuel seem to make the split worse bc B1 was stay at 51%(lean)
B1 WILL NOT COME DOWN.

I am LOST....

Last edited by Green3spd; 02-11-2013 at 12:02 AM.
Old 02-13-2013, 09:12 AM
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Anybody have any thoughts?
Old 02-13-2013, 09:18 AM
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Pm sent
Old 02-13-2013, 04:29 PM
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Originally Posted by quik95lt1
Pm sent
PM replied.
Old 03-23-2013, 06:48 PM
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Still battling this problem....any other thoughts?
Old 03-23-2013, 08:00 PM
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Have you swapped sides with the O2 sensors? If that changes nothing, swap sides with the injectors. Do you have an infrared rwhp gun? Shoot the header tubes on the lean side. If you have a cold tube there is a misfire. That will cause high fuel trim numbers on a bank that is not actually lean. Have you looked for black plugs on the high fuel trim side? Have you unplugged an O2 sensor to see if the scan tool shows that side stuck about 450 mv? I don't know how he did it , but I had one guy with O2s hooked the the wrong sides.
Old 04-09-2013, 12:04 AM
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Had a lifter collapse on me(which Comp took care of me on), so I pulled the intake and found a terrible leak at the bottom of the intake runner. So it was pulling air from the oil valley.

Fuel split fixed.

Thx for all the help along the way.



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